source: trunk/source/processes/electromagnetic/lowenergy/src/G4CrossSectionExcitationMillerGreenPartial.cc @ 836

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// $Id: G4CrossSectionExcitationMillerGreenPartial.cc,v 1.1 2007/11/08 19:57:23 pia Exp $
// GEANT4 tag $Name:  $
// 
// Contact Author: Maria Grazia Pia (Maria.Grazia.Pia@cern.ch)
//
// Reference: TNS Geant4-DNA paper
// Reference for implementation model: NIM. 155, pp. 145-156, 1978

// History:
// -----------
// Date         Name              Modification
// 28 Apr 2007  M.G. Pia          Created in compliance with design described in TNS paper
//
// -------------------------------------------------------------------

// Class description:
// Geant4-DNA Cross total cross section for electron elastic scattering in water
// Reference: TNS Geant4-DNA paper
// S. Chauvie et al., Geant4 physics processes for microdosimetry simulation:
// design foundation and implementation of the first set of models,
// IEEE Trans. Nucl. Sci., vol. 54, no. 6, Dec. 2007.
// Further documentation available from http://www.ge.infn.it/geant4/dna

// -------------------------------------------------------------------


#include "G4CrossSectionExcitationMillerGreenPartial.hh"
#include "G4Track.hh"
#include "G4DynamicParticle.hh"
#include "G4ParticleDefinition.hh"
#include "G4Proton.hh"
#include "G4DNAGenericIonsManager.hh"
#include "G4CrossSectionExcitationEmfietzoglouPartial.hh"
#include "Randomize.hh"
#include <deque>


G4CrossSectionExcitationMillerGreenPartial::G4CrossSectionExcitationMillerGreenPartial()
{

  nLevels = waterExcitation.NumberOfLevels();
  //G4cout << "Water excitation energy: number of levels = " << nLevels << G4endl;
  
  //PROTON
  kineticEnergyCorrection[0] = 1.;
  slaterEffectiveCharge[0][0] = 0.;
  slaterEffectiveCharge[1][0] = 0.;
  slaterEffectiveCharge[2][0] = 0.;
  sCoefficient[0][0] = 0.;
  sCoefficient[1][0] = 0.;
  sCoefficient[2][0] = 0.;

  //ALPHA++
  kineticEnergyCorrection[1] = 0.9382723/3.727417;
  slaterEffectiveCharge[0][1]=0.;
  slaterEffectiveCharge[1][1]=0.;
  slaterEffectiveCharge[2][1]=0.;
  sCoefficient[0][1]=0.;
  sCoefficient[1][1]=0.;
  sCoefficient[2][1]=0.;

  // ALPHA+
  kineticEnergyCorrection[2] = 0.9382723/3.727417;
  slaterEffectiveCharge[0][2]=2.0;
  slaterEffectiveCharge[1][2]=1.15;
  slaterEffectiveCharge[2][2]=1.15;
  sCoefficient[0][2]=0.7;
  sCoefficient[1][2]=0.15;
  sCoefficient[2][2]=0.15;

  // HELIUM
  kineticEnergyCorrection[3] = 0.9382723/3.727417;
  slaterEffectiveCharge[0][3]=1.7;
  slaterEffectiveCharge[1][3]=1.15;
  slaterEffectiveCharge[2][3]=1.15;
  sCoefficient[0][3]=0.5;
  sCoefficient[1][3]=0.25;
  sCoefficient[2][3]=0.25;  
  
}

G4CrossSectionExcitationMillerGreenPartial::~G4CrossSectionExcitationMillerGreenPartial()
{ }
 
G4double G4CrossSectionExcitationMillerGreenPartial::CrossSection(G4double k, G4int excitationLevel, 
                                                                  const G4ParticleDefinition* particleDefinition)
{
  //                               ( ( z * aj ) ^ omegaj ) * ( t - ej ) ^ nu
  // sigma(t) = zEff^2 * sigma0 * --------------------------------------------
  //                               jj ^ ( omegaj + nu ) + t ^ ( omegaj + nu )
  //
  // where t is the kinetic energy corrected by Helium mass over proton mass for Helium ions
  //
  // zEff is:
  //  1 for protons
  //  2 for alpha++
  //  and  2 - c1 S_1s - c2 S_2s - c3 S_2p for alpha+ and He
  //
  // Dingfelder et al., RPC 59, 255-275, 2000 from Miller and Green (1973)
  // Formula (34) and Table 2
  
  const G4double sigma0(1.E+8 * barn);
  const G4double nu(1.);
  const G4double aj[]={876.*eV, 2084.* eV, 1373.*eV, 692.*eV, 900.*eV};
  const G4double jj[]={19820.*eV, 23490.*eV, 27770.*eV, 30830.*eV, 33080.*eV};
  const G4double omegaj[]={0.85, 0.88, 0.88, 0.78, 0.78};
  
  G4int particleTypeIndex = 0;
  G4DNAGenericIonsManager* instance;
  instance = G4DNAGenericIonsManager::Instance();

  if (particleDefinition == G4Proton::ProtonDefinition()) particleTypeIndex=0;
  if (particleDefinition == instance->GetIon("alpha++")) particleTypeIndex=1;
  if (particleDefinition == instance->GetIon("alpha+")) particleTypeIndex=2;
  if (particleDefinition == instance->GetIon("helium")) particleTypeIndex=3;
 
  G4double tCorrected;
  tCorrected = k * kineticEnergyCorrection[particleTypeIndex];

  // Assume that the material is water; proper algorithm to calculate correctly for any material to be inserted here
  G4int z = 10;

  G4double numerator;
  numerator = std::pow(z * aj[excitationLevel], omegaj[excitationLevel]) * 
    std::pow(tCorrected - waterExcitation.ExcitationEnergy(excitationLevel), nu);

  G4double power;
  power = omegaj[excitationLevel] + nu;

  G4double denominator;
  denominator = std::pow(jj[excitationLevel], power) + std::pow(tCorrected, power);

  G4double zEff = particleDefinition->GetPDGCharge() / eplus + particleDefinition->GetLeptonNumber();

  zEff -= ( sCoefficient[0][particleTypeIndex] * S_1s(k, waterExcitation.ExcitationEnergy(excitationLevel), slaterEffectiveCharge[0][particleTypeIndex], 1.) +
            sCoefficient[1][particleTypeIndex] * S_2s(k, waterExcitation.ExcitationEnergy(excitationLevel), slaterEffectiveCharge[1][particleTypeIndex], 2.) +
            sCoefficient[2][particleTypeIndex] * S_2p(k, waterExcitation.ExcitationEnergy(excitationLevel), slaterEffectiveCharge[2][particleTypeIndex], 2.) );

  G4double cross = sigma0 * zEff * zEff * numerator / denominator;

  return cross;
}

G4int G4CrossSectionExcitationMillerGreenPartial::RandomSelect(G4double k, 
                                                               const G4ParticleDefinition* particle)
{
  G4int i = nLevels;
  G4double value = 0.;
  std::deque<double> values;
  
  // ---- MGP ---- The following algorithm is wrong: it works is the cross section 
  // is a monotone increasing function.
  // The algorithm should be corrected by building the cumulative function 
  // of the cross section and comparing a random number in the range 0-1 against
  // the cumulative value at each bin 

  G4DNAGenericIonsManager *instance;
  instance = G4DNAGenericIonsManager::Instance();

  // ELECTRON CORRECTION
 
  if ( particle == instance->GetIon("alpha++"))
    {  while (i > 0)
      {
        i--;
        G4double partial = CrossSection(k,i,particle);
        values.push_front(partial);
        value += partial;
      }

    value *= G4UniformRand();
    
    i = nLevels;

    while (i > 0)
      {
        i--;
        if (values[i] > value) return i;
        value -= values[i];
      }
    } 

  //
  // add ONE or TWO electron-water excitation for alpha+ and helium
   
  if ( particle == instance->GetIon("alpha+") 
       ||
       particle == instance->GetIon("helium")
       ) 
    {

      while (i>0)
        {
          i--;
         
          G4CrossSectionExcitationEmfietzoglouPartial* excitationXS = 
            new G4CrossSectionExcitationEmfietzoglouPartial();
         
          G4double sigmaExcitation=0;
          if (k*0.511/3728 > 7.4*eV && k*0.511/3728 < 10*keV) sigmaExcitation = excitationXS->CrossSection(k*0.511/3728,i);
 
          G4double partial = CrossSection(k,i,particle);
          if (particle == instance->GetIon("alpha+")) partial = CrossSection(k,i,particle) + sigmaExcitation;
          if (particle == instance->GetIon("helium")) partial = CrossSection(k,i,particle) + 2*sigmaExcitation;
          values.push_front(partial);
          value += partial;
          delete excitationXS;
        }
  
      value*=G4UniformRand();
  
      i=5;
      while (i>0)
        {
          i--;
   
          if (values[i]>value) return i;
  
          value-=values[i];
        }
    }    
  //    
  return 0;
}

G4double G4CrossSectionExcitationMillerGreenPartial::Sum(G4double k, const G4ParticleDefinition* particle)
{
  G4double totalCrossSection = 0.;

  for (G4int i=0; i<nLevels; i++)
    {
      totalCrossSection += CrossSection(k,i,particle);
    }
  return totalCrossSection;
}


G4double G4CrossSectionExcitationMillerGreenPartial::S_1s(G4double t,
                                                          G4double energyTransferred,
                                                          G4double slaterEffectiveCharge,
                                                          G4double shellNumber)
{
  // 1 - e^(-2r) * ( 1 + 2 r + 2 r^2)
  // Dingfelder, in Chattanooga 2005 proceedings, formula (7)
 
  G4double r = R(t, energyTransferred, slaterEffectiveCharge, shellNumber);
  G4double value = 1. - std::exp(-2 * r) * ( ( 2. * r + 2. ) * r + 1. );
  
  return value;
}


G4double G4CrossSectionExcitationMillerGreenPartial::S_2s(G4double t,
                                                          G4double energyTransferred,
                                                          G4double slaterEffectiveCharge,
                                                          G4double shellNumber)
{
  // 1 - e^(-2 r) * ( 1 + 2 r + 2 r^2 + 2 r^4)
  // Dingfelder, in Chattanooga 2005 proceedings, formula (8)

  G4double r = R(t, energyTransferred, slaterEffectiveCharge, shellNumber);
  G4double value =  1. - std::exp(-2 * r) * (((2. * r * r + 2.) * r + 2.) * r + 1.);

  return value;
 
}


G4double G4CrossSectionExcitationMillerGreenPartial::S_2p(G4double t,
                                                          G4double energyTransferred,
                                                          G4double slaterEffectiveCharge,
                                                          G4double shellNumber)
{
  // 1 - e^(-2 r) * ( 1 + 2 r + 2 r^2 + 4/3 r^3 + 2/3 r^4)
  // Dingfelder, in Chattanooga 2005 proceedings, formula (9)

  G4double r = R(t, energyTransferred, slaterEffectiveCharge, shellNumber);
  G4double value =  1. - std::exp(-2 * r) * (((( 2./3. * r + 4./3.) * r + 2.) * r + 2.) * r  + 1.);

  return value;
}


G4double G4CrossSectionExcitationMillerGreenPartial::R(G4double t,
                                                       G4double energyTransferred,
                                                       G4double slaterEffectiveCharge,
                                                       G4double shellNumber) 
{
  // tElectron = m_electron / m_alpha * t
  // Hardcoded in Riccardo's implementation; to be corrected
  // Dingfelder, in Chattanooga 2005 proceedings, p 4

  G4double tElectron = 0.511/3728. * t;
  G4double value = 2. * tElectron * slaterEffectiveCharge / (energyTransferred * shellNumber);
  
  return value;
}